New data to suport the phylogenetic relationship between the serial planktonic foraminifera (Family Heterohelicidae Cushman, 1927) and some large-sized benthic foraminifera (Family Orbitoididae Schwager, 1876) of the Late Cretaceous

New observations about the test variability and chamber morphology of the multiserial portion of the test confirm a plausible phylogenetic relationship between the planktonic foraminiferal genus Sigalia (Family Heterohelicidae) and the large-sized benthic genus with complex internal structure, Orbitoides (Family Orbitoididae), as suggested by KÜPPER (l 954). The biserial stage known from the microspheric forms of the early representatives of the genus Orbitoides from the Santonian show similarities with the planktonic foraminiferal species Sigalia carpatica. The multiserial stage of Sigalia decoratissima, a species which evolved from S. carpatica has subtriangular chambers in the last multiserial sets, which is similar to what is seen in the equatorial section of Orbitoides. A similar chamber arrangement in the multiserial stage is present in Sigalia rugocostata, a descendant from S. deflaensis. A phylogenetic relationship between Sigalia rugocostata and the earliest forms of Orbitoides however, could not be substantiated by the morphology of the biserial stage, which is different in the two taxa.